Blame - poky/documentation/ref-manual/faq.xml - openbmc/openbmc

2018-02-25 22:55:05 -0500

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I see lots of 404 responses for files when the OpenEmbedded

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build system is trying to download sources.

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Is something wrong?

Patrick Williams

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</para>

</question>

<para>

Nothing is wrong.

The OpenEmbedded build system checks any configured source mirrors before downloading

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from the upstream sources.

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The build system does this searching for both source archives and

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pre-checked out versions of SCM-managed software.

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These checks help in large installations because it can reduce load on the SCM servers

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themselves.

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The address above is one of the default mirrors configured into the

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build system.

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Consequently, if an upstream source disappears, the team

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can place sources there so builds continue to work.

</para>

</answer>

</qandaentry>

<para>

I have machine-specific data in a package for one machine only but the package is

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being marked as machine-specific in all cases, how do I prevent this?

</para>

</question>

<para>

Set <filename><link linkend='var-SRC_URI_OVERRIDES_PACKAGE_ARCH'>SRC_URI_OVERRIDES_PACKAGE_ARCH</link>

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</filename> = "0" in the <filename>.bb</filename> file but make sure the package is

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manually marked as

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machine-specific for the case that needs it.

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The code that handles

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<filename>SRC_URI_OVERRIDES_PACKAGE_ARCH</filename> is in

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the <filename>meta/classes/base.bbclass</filename> file.

</para>

</answer>

</qandaentry>

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2016-06-20 12:57:21 -0500

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I'm behind a firewall and need to use a proxy server. How do I do that?

</para>

</question>

<para>

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Most source fetching by the OpenEmbedded build system is done

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by <filename>wget</filename> and you therefore need to specify

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the proxy settings in a <filename>.wgetrc</filename> file,

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which can be in your home directory if you are a single user

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or can be in <filename>/usr/local/etc/wgetrc</filename> as

a global user file.

</para>

<para>

Following is the applicable code for setting various proxy

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types in the <filename>.wgetrc</filename> file.

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By default, these settings are disabled with comments.

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To use them, remove the comments:

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# You can set the default proxies for Wget to use for http, https, and ftp.

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# They will override the value in the environment.

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#https_proxy = http://proxy.yoyodyne.com:18023/

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#http_proxy = http://proxy.yoyodyne.com:18023/

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#ftp_proxy = http://proxy.yoyodyne.com:18023/

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# If you do not want to use proxy at all, set this to off.

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#use_proxy = on

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</literallayout>

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The Yocto Project also includes a

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<filename>meta-poky/conf/site.conf.sample</filename> file that

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shows how to configure CVS and Git proxy servers if needed.

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For more information on setting up various proxy types and

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configuring proxy servers, see the

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"<ulink url='&YOCTO_WIKI_URL;/wiki/Working_Behind_a_Network_Proxy'>Working Behind a Network Proxy</ulink>"

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Wiki page.

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</para>

</answer>

</qandaentry>

<para>

Andrew Geissler

c9f7865

2020-09-18 14:11:35 -0500

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What's the difference between <replaceable>target</replaceable> and <replaceable>target</replaceable><filename>-native</filename>?

Patrick Williams

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</para>

</question>

<para>

The <filename>*-native</filename> targets are designed to run on the system

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being used for the build.

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These are usually tools that are needed to assist the build in some way such as

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<filename>quilt-native</filename>, which is used to apply patches.

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The non-native version is the one that runs on the target device.

</para>

</answer>

</qandaentry>

<para>

I'm seeing random build failures. Help?!

</para>

</question>

<para>

If the same build is failing in totally different and random

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ways, the most likely explanation is:

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<listitem><para>The hardware you are running the build on

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has some problem.</para></listitem>

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<listitem><para>You are running the build under

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virtualization, in which case the virtualization

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probably has bugs.</para></listitem>

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</itemizedlist>

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The OpenEmbedded build system processes a massive amount of

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data that causes lots of network, disk and CPU activity and

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is sensitive to even single-bit failures in any of these areas.

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True random failures have always been traced back to hardware

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or virtualization issues.

</para>

</answer>

</qandaentry>

<para>

When I try to build a native recipe, the build fails with <filename>iconv.h</filename> problems.

</para>

</question>

<para>

If you get an error message that indicates GNU

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<filename>libiconv</filename> is not in use but

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<filename>iconv.h</filename> has been included from

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<filename>libiconv</filename>, you need to check to see if

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you have a previously installed version of the header file

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in <filename>/usr/local/include</filename>.

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#error GNU libiconv not in use but included iconv.h is from libiconv

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</literallayout>

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If you find a previously installed file, you should either

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uninstall it or temporarily rename it and try the build again.

</para>

<para>

This issue is just a single manifestation of "system

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leakage" issues caused when the OpenEmbedded build system

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finds and uses previously installed files during a native

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build.

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This type of issue might not be limited to

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<filename>iconv.h</filename>.

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Be sure that leakage cannot occur from

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<filename>/usr/local/include</filename> and

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<filename>/opt</filename> locations.

</para>

</answer>

</qandaentry>

<para>

What do we need to ship for license compliance?

</para>

</question>

<para>

This is a difficult question and you need to consult your lawyer

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for the answer for your specific case.

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It is worth bearing in mind that for GPL compliance, there needs

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to be enough information shipped to allow someone else to

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rebuild and produce the same end result you are shipping.

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This means sharing the source code, any patches applied to it,

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and also any configuration information about how that package

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was configured and built.

</para>

<para>

You can find more information on licensing in the

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"<ulink url='&YOCTO_DOCS_OM_URL;#licensing'>Licensing</ulink>"

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section in the Yocto Project Overview and Concepts Manual

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and also in the

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"<ulink url='&YOCTO_DOCS_DEV_URL;#maintaining-open-source-license-compliance-during-your-products-lifecycle'>Maintaining Open Source License Compliance During Your Product's Lifecycle</ulink>"

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section in the Yocto Project Development Tasks Manual.

Patrick Williams

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</para>

</answer>

</qandaentry>

<para>

How do I disable the cursor on my touchscreen device?

</para>

</question>

<para>

You need to create a form factor file as described in the

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"<ulink url='&YOCTO_DOCS_BSP_URL;#bsp-filelayout-misc-recipes'>Miscellaneous BSP-Specific Recipe Files</ulink>"

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section in the Yocto Project Board Support Packages (BSP)

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Developer's Guide.

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Set the <filename>HAVE_TOUCHSCREEN</filename> variable equal to

one as follows:

HAVE_TOUCHSCREEN=1

</literallayout>

</para>

</answer>

</qandaentry>

<para>

How do I make sure connected network interfaces are brought up by default?

</para>

</question>

<para>

The default interfaces file provided by the netbase recipe does not

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automatically bring up network interfaces.

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Therefore, you will need to add a BSP-specific netbase that includes an interfaces

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file.

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See the "<ulink url='&YOCTO_DOCS_BSP_URL;#bsp-filelayout-misc-recipes'>Miscellaneous BSP-Specific Recipe Files</ulink>"

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section in the Yocto Project Board Support Packages (BSP)

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Developer's Guide for information on creating these types of

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miscellaneous recipe files.

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</para>

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<para>

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For example, add the following files to your layer:

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meta-MACHINE/recipes-bsp/netbase/netbase/MACHINE/interfaces

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meta-MACHINE/recipes-bsp/netbase/netbase_5.0.bbappend

</literallayout>

</para>

</answer>

</qandaentry>

<para>

How do I create images with more free space?

</para>

</question>

<para>

By default, the OpenEmbedded build system creates images

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that are 1.3 times the size of the populated root filesystem.

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To affect the image size, you need to set various

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configurations:

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<listitem><para><emphasis>Image Size:</emphasis>

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The OpenEmbedded build system uses the

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variable to define the size of the image in Kbytes.

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The build system determines the size by taking into

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account the initial root filesystem size before any

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modifications such as requested size for the image and

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any requested additional free disk space to be

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added to the image.</para></listitem>

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<listitem><para><emphasis>Overhead:</emphasis>

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Use the

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variable to define the multiplier that the build system

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applies to the initial image size, which is 1.3 by

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default.</para></listitem>

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<listitem><para><emphasis>Additional Free Space:</emphasis>

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Use the

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variable to add additional free space to the image.

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The build system adds this space to the image after

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it determines its

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<filename>IMAGE_ROOTFS_SIZE</filename>.

</para></listitem>

</itemizedlist>

</para>

</answer>

</qandaentry>

<para>

Why don't you support directories with spaces in the pathnames?

</para>

</question>

<para>

The Yocto Project team has tried to do this before but too

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many of the tools the OpenEmbedded build system depends on,

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such as <filename>autoconf</filename>, break when they find

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spaces in pathnames.

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Until that situation changes, the team will not support spaces

in pathnames.

</para>

</answer>

</qandaentry>

<para>

How do I use an external toolchain?

</para>

</question>

<para>

The toolchain configuration is very flexible and customizable.

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It is primarily controlled with the

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<filename><link linkend='var-TCMODE'>TCMODE</link></filename>

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variable.

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This variable controls which <filename>tcmode-*.inc</filename>

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file to include from the

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<filename>meta/conf/distro/include</filename> directory within

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the

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Patrick Williams

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</para>

<para>

The default value of <filename>TCMODE</filename> is "default",

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which tells the OpenEmbedded build system to use its internally

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built toolchain (i.e. <filename>tcmode-default.inc</filename>).

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However, other patterns are accepted.

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In particular, "external-*" refers to external toolchains.

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One example is the Sourcery G++ Toolchain.

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The support for this toolchain resides in the separate

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<filename>meta-sourcery</filename> layer at

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<ulink url='http://github.com/MentorEmbedded/meta-sourcery/'></ulink>.

</para>

<para>

In addition to the toolchain configuration, you also need a

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corresponding toolchain recipe file.

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This recipe file needs to package up any pre-built objects in

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the toolchain such as <filename>libgcc</filename>,

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<filename>libstdcc++</filename>, any locales, and

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<filename>libc</filename>.

</para>

</answer>

</qandaentry>

How does the OpenEmbedded build system obtain source code and

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will it work behind my firewall or proxy server?

</para>

</question>

<para>

The way the build system obtains source code is highly

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configurable.

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You can setup the build system to get source code in most

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environments if HTTP transport is available.

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</para>

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<para>

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When the build system searches for source code, it first

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tries the local download directory.

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If that location fails, Poky tries

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the upstream source, and then

in that order.

</para>

<para>

Assuming your distribution is "poky", the OpenEmbedded build

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system uses the Yocto Project source

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<filename>PREMIRRORS</filename> by default for SCM-based

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sources, upstreams for normal tarballs, and then falls back

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to a number of other mirrors including the Yocto Project

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source mirror if those fail.

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</para>

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<para>

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As an example, you could add a specific server for the

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build system to attempt before any others by adding something

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like the following to the <filename>local.conf</filename>

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configuration file:

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PREMIRRORS_prepend = "\

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git://.*/.* http://www.yoctoproject.org/sources/ \n \

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ftp://.*/.* http://www.yoctoproject.org/sources/ \n \

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http://.*/.* http://www.yoctoproject.org/sources/ \n \

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https://.*/.* http://www.yoctoproject.org/sources/ \n"

</literallayout>

</para>

<para>

These changes cause the build system to intercept Git, FTP,

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HTTP, and HTTPS requests and direct them to the

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<filename>http://</filename> sources mirror.

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You can use <filename>file://</filename> URLs to point to

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local directories or network shares as well.

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</para>

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<para>

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Aside from the previous technique, these options also exist:

BB_NO_NETWORK = "1"

</literallayout>

This statement tells BitBake to issue an error instead of

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trying to access the Internet.

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This technique is useful if you want to ensure code builds

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only from local sources.

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</para>

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<para>

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Here is another technique:

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BB_FETCH_PREMIRRORONLY = "1"

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</literallayout>

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This statement limits the build system to pulling source

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from the <filename>PREMIRRORS</filename> only.

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Again, this technique is useful for reproducing builds.

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</para>

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<para>

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Here is another technique:

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652

BB_GENERATE_MIRROR_TARBALLS = "1"

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</literallayout>

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This statement tells the build system to generate mirror

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tarballs.

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This technique is useful if you want to create a mirror server.

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If not, however, the technique can simply waste time during

the build.

</para>

<para>

Finally, consider an example where you are behind an

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HTTP-only firewall.

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You could make the following changes to the

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<filename>local.conf</filename> configuration file as long as

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the <filename>PREMIRRORS</filename> server is current:

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PREMIRRORS_prepend = "\

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ftp://.*/.* http://www.yoctoproject.org/sources/ \n \

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http://.*/.* http://www.yoctoproject.org/sources/ \n \

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https://.*/.* http://www.yoctoproject.org/sources/ \n"

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BB_FETCH_PREMIRRORONLY = "1"

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</literallayout>

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These changes would cause the build system to successfully

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fetch source over HTTP and any network accesses to anything

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other than the <filename>PREMIRRORS</filename> would fail.

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</para>

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<para>

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The build system also honors the standard shell environment

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variables <filename>http_proxy</filename>,

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<filename>ftp_proxy</filename>,

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<filename>https_proxy</filename>, and

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<filename>all_proxy</filename> to redirect requests through

proxy servers.

</para>

<note>

You can find more information on the

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"<ulink url='&YOCTO_WIKI_URL;/wiki/Working_Behind_a_Network_Proxy'>Working Behind a Network Proxy</ulink>"

Wiki page.

</note>

</answer>

</qandaentry>

<para>

Can I get rid of build output so I can start over?

</para>

</question>

<para>

Yes - you can easily do this.

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When you use BitBake to build an image, all the build output

703

goes into the directory created when you run the

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build environment setup script (i.e.

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By default, this

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is named <filename>build</filename> but can be named

anything you want.

</para>

<para>

Within the Build Directory, is the <filename>tmp</filename>

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directory.

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To remove all the build output yet preserve any source code or

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downloaded files from previous builds, simply remove the

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<filename>tmp</filename> directory.

</para>

</answer>

</qandaentry>

<para>

Why do <filename>${bindir}</filename> and <filename>${libdir}</filename> have strange values for <filename>-native</filename> recipes?

</para>

</question>

<para>

Executables and libraries might need to be used from a

731

directory other than the directory into which they were

732

initially installed.

733

Complicating this situation is the fact that sometimes these

734

executables and libraries are compiled with the expectation

735

of being run from that initial installation target directory.

736

If this is the case, moving them causes problems.

</para>

<para>

This scenario is a fundamental problem for package maintainers

741

of mainstream Linux distributions as well as for the

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OpenEmbedded build system.

743

As such, a well-established solution exists.

744

Makefiles, Autotools configuration scripts, and other build

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systems are expected to respect environment variables such as

746

<filename>bindir</filename>, <filename>libdir</filename>,

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and <filename>sysconfdir</filename> that indicate where

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executables, libraries, and data reside when a program is

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actually run.

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They are also expected to respect a

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<filename>DESTDIR</filename> environment variable, which is

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prepended to all the other variables when the build system

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actually installs the files.

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It is understood that the program does not actually run from

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within <filename>DESTDIR</filename>.

</para>

<para>

When the OpenEmbedded build system uses a recipe to build a

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target-architecture program (i.e. one that is intended for

761

inclusion on the image being built), that program eventually

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runs from the root file system of that image.

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Thus, the build system provides a value of "/usr/bin" for

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<filename>bindir</filename>, a value of "/usr/lib" for

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<filename>libdir</filename>, and so forth.

</para>

<para>

Meanwhile, <filename>DESTDIR</filename> is a path within the

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However, when the recipe builds a native program (i.e. one

772

that is intended to run on the build machine), that program

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is never installed directly to the build machine's root

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file system.

775

Consequently, the build system uses paths within the Build

776

Directory for <filename>DESTDIR</filename>,

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<filename>bindir</filename> and related variables.

778

To better understand this, consider the following two paths

779

where the first is relatively normal and the second is not:

780

<note>

781

Due to these lengthy examples, the paths are artificially

782

broken across lines for readability.

783

</note>

784

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/home/maxtothemax/poky-bootchart2/build/tmp/work/i586-poky-linux/zlib/

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1.2.8-r0/sysroot-destdir/usr/bin

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/home/maxtothemax/poky-bootchart2/build/tmp/work/x86_64-linux/

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zlib-native/1.2.8-r0/sysroot-destdir/home/maxtothemax/poky-bootchart2/

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build/tmp/sysroots/x86_64-linux/usr/bin

791

</literallayout>

792

Even if the paths look unusual, they both are correct -

793

the first for a target and the second for a native recipe.

794

These paths are a consequence of the

795

<filename>DESTDIR</filename> mechanism and while they

796

appear strange, they are correct and in practice very effective.

</para>

</answer>

</qandaentry>

<para>

Patrick Williams

2016-06-20 12:57:21 -0500

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804

The files provided by my <filename>*-native</filename> recipe do

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2015-09-15 14:41:29 -0500

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805

not appear to be available to other recipes.

806

Files are missing from the native sysroot, my recipe is

807

installing to the wrong place, or I am getting permissions

808

errors during the do_install task in my recipe! What is wrong?

</para>

</question>

<para>

This situation results when a build system does

814

not recognize the environment variables supplied to it by

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2018-02-25 22:55:05 -0500

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Patrick Williams